Question

A stone is dropped from a balloon moving upwards at 20m\s at height of 5 m. Distance travellrd by the stine just before reaching the ground

Answer 1

Explanation

A balloon is rising steadily at 5m/s. when it reaches a height of 30 m, a stone is dropped from it. After how much time will the stone reach the ground ?

(a)t=1s(b)t=2s(c)t=1.5s(d)t=3s

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A)

When stone is dropped from a rising balloon it has a initial velocity of 5m/s in upward direction.

Taking downward direction as positive and

s=ut+12ut2

30=−5×t+12×10×t2

5t2−5t−30=0

t2−t−6=0

(t−3)or(t+2)=0

t=3ort=−2(t=−2 negative time is not possible)

Therefore t=3s

Hence d is the correct answer.

Answer 2

Answer:

s=it+12ut

30=-5×t+12×10

5t2-5t-30=0

t2-t-6=0

(t=+3)or( t=-2)

t=3